A multidisciplinary International Collaborative Biodiversity Group is proposed that will discover, isolate, and preclinically evaluate pharmacologically important species from Mexico, the third richest mega- diversity region of the world and one of the most threatened in terms of biodiversity loss due to increased environmental destruction. Work will be carried out among the Maya-speaking peoples of the area who possess a complex ethnopharmacopoeia comprised of hundreds of species of plants in an ancient system of traditional medicine. The efficacy of the most important plant species employed in Maya medicine, as well the pharmaceutically most promising species from the total flora of Highland Chiapas (approximately 5000 species) will be evaluated by natural products chemists employing the most modern assaying procedures available. A significant sample of micro-organisms from the region will also be evaluated. All species will be screened for their activity against cancer, opportunistic diseases associated with HIV-AIDS, CNS disorders, contraception, cardiovascular disease, and locally serious gastrointestinal, respiratory/pulmonary, and skin disorders. The ICBG will mount a comprehensive botanical survey of the Central Chiapas Highlands, in concert with agroecological experimentation on sustainable harvest and production of selected species that show high potential as pytomedicinals, crop protection agents, and commercially viable ornamentals. Maya collaborators will be trained in workshops and participatory research activities. Academic exchanges developed with the ICBG will allow host-country nationals and US students to participate in advanced degree programs, assuring that goals of the program will be continued upon its completion.